Yes unfortunately the X3 is notorious for springing leaks in the washer fluid pumps that are on the washer tank under the hood. The good news is that it's an easy DIY fix. My 2006 drained all its fluid and then again after about week once filled. I noticed it was leaking right at the pump/grommet so I tried replacing the strainer grommet first but it was the pump so i replaced the pump that was leaking. To help others that may come across this i created the following tutorial/photo document of the replacement:
BMW X3 Washer Fluid Pump Replacement DIY Guide
You can fix it for about $35 in parts and save a ton of money over what the dealer would charge (mine quoted $65 for the pump alone so installated would be well over $100).